"A good jingle catches the customer's attention and makes him (or her) think twice about a product; a bad jingle might make a company famous for the wrong reasons, or dissuade people from looking at a certain brand," writes study author Iveta Karailievová.

You can hear the famous McDonald's jingle at the end of this 2015 commercial:

They don't let you forget them.

You might think you're sick of a commercial the tenth time you see it, but advertisers know better: The more times you're exposed to their product, the more likely you are to remember it ... and maybe even buy it.

"The positive emotions that are linked to the celebrity get transferred to the product," Stallen told the Naked Scientists. "Next time, if you see those products like in a shop or a sale, you have some positive associations with it." She goes on to explain that these positive associates appear to come from memories linked with that famous face.

For instance, Jennifer Hudson makes you "believe" in this 2011 Weight Watchers ad:

Stephen Curry, member of the Golden State Warriors, helped Under Armour raise their sales after he appeared in their campaign in 2015.Youtube / Under Armour

They put you in an athlete's shoes.

Sports are big.

Sportswear company Under Armour has seen a 95% rise in revenue after using sports superstars like NBA basketball player Stephen Curry, star ballerina Misty Copeland, and pro golfer Jordan Spieth in their 2015 campaigns.

They use regular people who are just like you.

In some cases, "regular people" can be even more effective than celebrities.

Lucia Moses at AdWeek explains that in an age of reality shows and internet transparency, celebrities are losing some of their shine. In their place, real people representing the typical consumer step up. "The result is creative that stands in stark, sometimes even gritty contrast to the typical super-slick TV spot," Moses writes.

For instance, who can forget Dove's classic "Real Beauty," which was considered one of the most successful ad campaigns of 2013?

They offer deals for a limited time only.

Some TV commercials feature limited-edition products or show deals that are available for a "limited time only."

As The Wall Street Journal reports, this is one of the most popular ways for companies to get shoppers to go out and buy. Putting a constraint on time or availability makes people feel an urgency to pull the trigger and spend.

Here's Red Lobster's commercial for the Lobsterfest, an event that only comes once a year: